Digestibility of spineless cactus meals in extruded diets for Nile tilapia (Oreochromis niloticus): energy, protein, amino acids, and carbohydrates

The aim of the present study was to determine the apparent digestibility coefficients (ADCs) of gross energy, dry matter, crude protein, amino acids, and different carbohydrate fractions of spineless cactus meals (SCMs) for Nile tilapia juveniles, fed with extruded diets. Fish were fed a reference diet or one of five test diets, each of which included 70% reference diet and 30% corresponding SCM. Fecal collection was performed in modified Guelph method. The ADCs for dry matter, gross energy, and soluble carbohydrates of the “redonda” spineless cactus meal (RSCM) were higher (P < 0.05) than those of either the “IPA 20” spineless cactus meal (ISCM) or “gigante” spineless cactus meal (GSCM), and the ADCs for crude protein of the RSCM and “Orelha de elefante africana” spineless cactus meal (OEASCM) were higher than those of the other cactus meals (P < 0.05). In addition, the ADCs for dry matter, crude protein, and gross energy of the SCMs were similar to wheat middlings. The digestibility of the less soluble fraction of the evaluated carbohydrates, the non-fibrous carbohydrates, varied between 58.32 and 73.04%, indicating efficiency in the digestion and absorption process. The data obtained in this article can be the basis for growth experiments, with the substitution of traditional ingredients for SCMs. The determination of zootechnical, physiological, metabolic, and health variables can indicate the potential for using SCMs in diets for Nile tilapia.